The invention described herein relates to a furan polymer impregnated wood which is uniform in colour and density throughout the treated zone. In order to obtain the polymer impregnated wood, a parent wood has been impregnated with a polymerizable furfural alcohol monomer solution containing at least water, stabilizers, and furfuryl alcohol, and at least one further compound. The invention also relates to a method for preparing a furan polymer impregnated wood and uses thereof.
Currently, wood is chemically preserved (protected from biodeterioration) mainly by using toxic preservatives. Most of these preservatives also have toxicity to other organisms in the environment, including humans. Even if they are well-fixed in wood, their presence presents a problem for end-of-use. Two approaches which are designed to use more environmentally-friendly chemicals are i) use of water-soluble salts which have low toxicity and ii) use of non-toxic chemicals which react with and alter the wood cell walls, making them less susceptible to biodeterioration.
Approach i) has the drawback that such salts usually leach out of wood in contact with water, limiting their usefulness. Boron and copper compounds have been used in this way. They have the advantage that some such salts act as fire retardants as well as reducing biodeterioration.
An example of approach ii) is the subject of a previous invention disclosed by Schneider (NO-A-20005137) based on furfuryl alcohol (FA) treating formulations. This previous invention used an undiluted treating solution, and treated the wood to high levels of retention. For woods with specific gravity near 0.30 (such as pine), the retention of chemical may approach 200% of the weight of the dry wood. For denser woods (about 0.60 specific gravity, such as maple and beech) retention can be in the 100% range. This level of retention has been shown to give excellent protection from biodeterioration, high dimensional stability in varying moisture conditions and an increase in most mechanical properties, particularly hardness. The main disadvantage with this treatment is the large amount of chemical used and the resulting cost.
Furfuryl alcohol is highly water soluble and therefore easily forms a uniform solution with water which can be used to impregnate wood. Therefore, FA impregnating solutions containing different amounts of water are easily made. However, there are things which must be overcome before a useful wood polymer composite can be made. First, after being impregnated into wood, the solution must be polymerized to be useful. Second, the polymerization must occur in wet or dry wood. Third, the polymerization must occur at fairly low temperatures.
Chemical initiators therefore must be added to the FA to make it polymerize in the desired temperature range and in wet or dry wood. How to initiate FA and make it polymerize in the desired temperature range is known from NO-A-20005137. However, the initiated FA from that technology does not mix well with water. Combing them causes the mixtures to separate into two components which cannot be uniformly impregnated into wood.
One object of the invention is to provide a furan polymer impregnated wood by altering the wood cell wall with the same chemical monomer as that disclosed in NO-A-20005137 but using smaller amounts of chemical.
Another object of the invention is to provide a uniform distribution of the chemicals in the furan polymer impregnated wood which causes uniform colour and density throughout the treated zone, by using water as an environmentally-friendly and production-friendly diluent which would permit uniform but low retention of active chemical in the treated zone of the wood.
Still another object of the invention is to provide a furan polymer impregnated wood having improved properties as regards dimensional stability, rot resistance, i.a.
According to the present invention, the foregoing and other objects are attained by a product, method and uses thereof as disclosed herein.